1. The Field of the Invention
The present invention relates to a stretchable device for use in a variety of applications including physical exercise.
2. The Background Art
Stretchable members have numerous applications for use in fastening, bundling, and otherwise generally containing objects. The stretch ability of such members makes them ideal for such purposes. Stretchable members also have application in exercising. The durability and stretch resistance of certain stretchable members makes them ideal for repetitive movements required in exercising.
One common stretchable member known in the art is the bungee cord. A typical bungee cord is comprised of multiple stretchable rubber fibers or strands throughout the center. A fabric is then woven around the rubber fibers. During manufacture of a bungee cord, the elastic strands are pulled through a loom that weaves the external fabric around it. Without the exterior fabric the elastic strands would fall out. The exterior fabric stays in full contact with the interior rubber fibers at all times during the stretch.
Because of the manufacturing techniques, the internal material used, and the weave of the external fabric, the bungee cord technology has limits. In practice, the maximum stretch of a bungee cord is about twice its original length. In practice, a bungee cord generally has a maximum stretch of only 1.5 to 1.75 times its original length.
Another stretchable member known in the art incorporates an elastic within an elastic. In this approach, a small tubular elastic is threaded through an identical but larger tubular elastic. Both elastics are commonly of the same material. If one elastic or the other were to break it would keep both elastics contained together. However, the use of two members of the same material does not substantially limit the stretch. Thus, the members are susceptible to stretching beyond a safe limit. This may result in breaking of the members and possible injury to the user.
Another approach in the art is the use of an elastic and rope in combination. In this approach, an elastic has a rope spiraled along the exterior length of the elastic. The rope is then attached to the eyelets at the end of the elastic. A disadvantage with this approach is the entanglement of the rope which hinders the function of the stretchable member. A further disadvantage is that if the elastic breaks the user may be injured by the whiplash of the elastic.
The prior art suffers from having limited stretching capability and not having a safety limitation to prevent undue stretching. Thus, it is an object of the invention to provide a stretching device with superior stretching capability and safety features to protect the device and the user. These advantages of the present invention will become more fully apparent by examination of the following description of the preferred embodiments and the accompanying drawings.